Lubricating system for refrigerator motor-compressors



Octr31, 1950 Ec RowLEDGE E'I'AL 2,527,657

LUBRICA'I' c SYSTEM FOR REFRIGERATOR IOTOR-COIPRESSORS Filed Dec. 3,1946 3 Sheets-Sheet l m; INVENTORS W I Ema GEORGE ROWLEDGE BY JOSHUAWRLSON KITSQN ATTORNEY E. s. ROWLEDGE EI'AL 2,527,657 LUBRICATING SYSTEMFOR mxcsm'ron Oct.'3l, 1950 IOTOR-COIPRESSORS 3 Sheets-Sheet 2 FiledDec. s, 1946 INVENTORS ERIC QEORGE ROWLEDGE JosHpA wmsou KITSON ATTORNEY31, 1950 E. anowuznss EI'AL 2,527,657

LUBRICATING sys'rm roa mum-ma IOTOR-COIPRESSORS 4 Filed Dec. s, 1946 sSheets-Sheet s 1N VENT 0185 ERIC GEORGE Rowuanea JOSHUA WILSON KITSONPatented Oct. 31, 1950 UNITED STATES PATENT OFFICE LUBRICATING SYSTEMFOR REFRIG- ERATOR MOTOR-COMPRESSORS Application December 3, 1946,Serial No. 713,748 In Great Britain September 26, 1944 Section 1, PublicLaw 690, August 8, 1946 Patent expires September 26, 1964 8 Claims.

In refrigerating systems of the motor-compressor type it is well knownthat where the compressor itself is of the type having a. large crankcase volume with respect to ie displacement of the cylinder, there isrelatively little pressure change in the crank case so that the fiow oflubricant along the piston into the bearing space between the top of thepiston and the cylinder head is not assisted since the mean pressureabove the piston is always greater than that below the piston andconsequently, particularly where pistons having no piston rings areused, the upper half of the piston and the suction and discharge valvesare starved of oil with a consequent reduction in the efliciency of thecompressor and an increase in the general noise level of the valvemechanism.

The object of the present invention is to provide a compressor of thistype which does not suffer from the above disadvantages and accord ingto the invention the valves and upper portions of the cylinder of amotor-driven compressor for a refrigerating unit are lubricated bymetering lubricant through a gauze restrictor into or adjacent to therefrigerant vapour stream as it passes to the compressor on the suctionstroke thereof, whereby the lubricant is converted to a fine mistentrained in the vapour. In one form of the invention refrigerant vapouris passed through a silencer into passages drilled in the cylindercasting, whence it passes to the valve chamber. The passages in thecompressor casting communicate with an oil sump and are fitted with agauze restrictor to provide a choke at which oil will be entrainedmetered into the suction gas stream and be finely atomised. In this formit will be carried into the valve chamber in suspension, passin thesuction valve of the compressor and wetting it with oil as it passes.The top portion of the cylinder will be similarly wetted as will thedischarge valve on the exhaust stroke. The oil carried through with thedischarge gas will mix with the circulatingrefrigerant in the usualmanner to be returned with the refrigerant vapour from the evaporator tobe rectified in any well known manner.

The restrictor may be in the form of a gauze and foil cylinder fittedwithin the passage in the compressor casting. An alternativearrangement, contemplates the direct entry of the refrigerant vapour tothe cylinder head or valve chamber, the oil being metered into saidvapour from a sump through an orifice in the compressor casting, whichorifice is closed by a gauze and retainer plate. With such anarrangement the oil is requ' to enter the orifice at the outer edges ofthe gauze and this provides a larger filter area. Furthermore, the gauzewill be held between the valve plate, which has a lapped finish, and theretainer plate, which may have a ground finish, so that variations inthe oil flow due to variations in the surface finish, are eliminated.

The invention is illustrated in the accompanying drawings of whichFigure l is a vertical section of a motor-compressor unit of thehermetically sealed type with parts omitted which do not form anyfeature of this invention, whilst Figure 2 is a section on the line 2-2of Figure 1.

Figure 3 is an exploded view of the gauze and foil cylinder of Figure 1.

Figures 4, 5 6 are fragmentary views of the part of the motor-compressorunit shown within the circle Hill of Figure 1 illustratingmodifiications of the invention.

Figure '7 shows a slight modification of Figure 4, whilst Figures 8 and9 show details of alternative forms of gauze and retainer as used withthe arrangements shown in Figures 4 to 7 respectively.

Referring to Figure l, the rotor A of an electric motor M drives thecrankshaft C which operates the piston P in the cylinder Y. A sump Sprovides lubricant for oiling all the working parts of the machine. Awell or auxiliary sump I0 is provided in the stator casting II which ismaintained full of oil by overflow from the main bearing 12 of thecrankshaft C. The refrigerant gas is drawn through a silencer l4 andalong a down-pipe 15 to a passage 38 drilled in the statorcasting H.Inserted in this passage and immediately before the passage l3 throughthe valve plate I! to the cylinder head I 8 is a restrictor and filterin the form of a gauze and foil cylinder 34, 35 held in the passage 38by a clip 36. Lubricant from the well H! is conveyed via a passage 31and a small hole 39 to the passage 38 whence it passes through thegauze, between the wall of passage 38 and the foil and thus as thesuction gas passes through the passage 38 it draws with it lubricantwhich becomes finely atomised, passes to the suction side 24 of thecylinder head and is drawn in to the cylinder Y by the piston P and thewalls of the cylinder Y, after which it passes through the dischargevalve 29 which is in turn lubricated, the oil then passing, entrained inthe discharge gas, via the pipe 23, silencer 26 and outlet pipe 28,throughout the system, ultimately to be rectified in the relatively warmreceptacle 39 formed in the stator frame, the separated oil beingconveyed to the main sump S via a small hole 32 formed in the bottomofthe receptacle, whilst the refrigerant vapour passes via the openin 33for the cycle to be repeated.

In the modification of Figure 4 the refrigerant vapour is conveyeddirectly from the silencer via the suction inlet 49 to the cylinder head24. Oil from the sump Hi due to the pressure difference between theparts A and B, is drawn through the opening 4| to the chamber 42, Theorifice 4.3 leading from the chamber 42 to the cylinder head is coveredby a gauze 44 and retainer plate 45, secured for example by means ofhammer drive screws. Oil runs down the outer-face of the valve plate I!until it reaches the suction port 21 where it is picked up by therefrigerant vapour and atomised as before.

' The somewhat similar arrangement of Figure 5 shows a gauze 4'! andretainer plate 48 held in position by means of a coiled spring 49.

In Figure 6, the refrigerant vapour is drawn through the inlet pipe 59,leading directly into the cylinder head 24 and the oil orifice 5!,closed by the gauze 44 and retainer 45, leads directly into the pipe 50so that atomisation of the oil in the vapour stream is improved.

In Figure 7 which shows an arrangement very similar to that shown inFigure 5, the oil'after leaving the orifice 43 is constrained to trickledown a capillary slot' 53 cut in the face of the valveplate 11,to-prevent spreading of. the oil and to ensureits concentration at theperiphery of the inlet port.

Figure 8 shows the gauze 44 and retainer plate 45 punched for receptionof the hammer drive screws, whilst Figur 9 shows a modified auze 4'1 andretainer 48v as might be used in the arrangement shown in Figure 5.

The amount of oil flowing through the restrictor is dependent upon threefactors viz. (a) the pressure drop between the areas 24 and B (seeFigure 4), (b) the gauze area and size of mesh and (c) the viscosity ofthe oil. By variation particularly of factor b the oil fiowcan beadjusted as desired to suit any particular machine.

We claim:

1. A motor-compressor unit for refrigerating systems of the vapourcompression type, including a cylinder, a valve plate, a cylinder head,suction and delivery ports in said valve plate, suction and deliverychambers in the cylinder head, an inlet in said valve plate and cylinderhead for refrigerant vapour, an oil sump, means for conveying oil fromsaid sump to said inlet and a cylinder of gauze telescopingly fitted insaid inlet and a cylindrical cover on the insideof said gauze forforcing oil on its Way from said means to said inlet to pass in axialdirection through said gauze cylinder between the surface of the inletand said cover. v

2. A motor-compressor unit for refrigerating systems of the vapourcompression type, including a cylinder, a valve plate, a cylinder head,suction and delivery ports in said valve plate, suction and deliverychambers in the cylinder head, an inlet in said valve plate forrefrigerant vapour, an oil sump, means for conveying oil from said sumpto said inlet including a passage through said valve plate, a gauze disccovering said passage, and another solid disc covering said gauze.

disc forcing the oil on its way to said passage to pass through thegauze disc between the valve plate and said solid disc.

3. A motor-compressor unit for a refrigerating system of the vapourcompression type, including a cylinder, a cylinder head, a valve plate,suction and delivery ports in said valve plate, suction and deliverychambers in said head, an inlet port in said valve plate to said suctionchamber, means for conveying lubricant to said inlet port, a gauzerestrictor in said inlet port, and a capillary slot formed in the faceof said valve plate to constrain lubricant to trickle from said inletport along said valve plate to concentrate at the periphery of thesuction port.

4. In a refrigerating system of the vapourcompression type having asuction duct for the' refrigerant vapor, a wall separating said suctionduct from a lubricant supply and a passage through said 'wall, a gauzesheet held between one surface of said wall and a cover plate, saidgauze sheet and cover plate overlying and extending beyond said passageso that the lubricant on its Way to the suction duct has to pass throughsaid gauze sheet in the direction of the plane thereof.

5. In a compressor for a refrigerating system of the vapour-compressiontype, .a cylinder body for a reciprocatingly driven piston, a cylinderhead and a valve plate between said cylinder head and said .cylinderbody, a suction duct in said cylinder head communicating over .a suctionport and valve on said valve plate with the interior of the cylinderbore, a recess formed in the end of the cylinder body at the .side ofand spaced from the cylinder bore and communicating with a source ofliquid lubricant, said valve plate closing said recess and beingprovided with a passage connecting the recess with the suction duct, agauze plate covering and extending beyond said passage on the side ofthe valve plate facing said recess, a cover plate for said gauze plateand means for holding said cover plate against the gauze plate and thevalve plate so that lubricant from said recess on its way to saidpassage has to flow from the outer margins of the gauze plate throughthe gauze between the surface-of .the valve plate and said coverplate,'thereby acting as a filter and as a metering device controllingthe amount of lubricant admitted to the suction duct.

6. A lubricant metering and filtering device for vapor compression typerefrigerating systems, comprising a hollow duct adapted for connecting asource of lubricant with the suction duct for the refrigerant vapor,said duct being formed at least in part by two closely-spaced wallsfirmly holding between them a 'piece of gauze so that lubricant has tofiowlongitudinally through said gauze thereby filtering the lubricantand controlling the rate of its admission to the suction duct. V L

7. A lubricant "metering and filtering device for vapor compression typerefrigerating systems, comprising a hollow duct adapted for connecting asource of lubricant with the suction duct for the refrigerant vapor,said duct being formed in part by two closely-spaced plane walls firmlyholding between them a plane sheet of gauze, a passage in one of saidwalls communicating respectively with a central portion of said spaceand with said suction duct whereas a peripheral region of said spaceopens toward the source of lubricant, the arrangement being 'so thatlubricant has to flow longitudinally through said gauze, thereby,filtering the lubricant and controlling the rate of its admission to thesuction duct. I

5 8. A lubricant metering and filtering device for REFERENCES CITEDvapor compression type refrigerating systems The following referencesare of record in the comprising a hollow duct adapted for connectingfile of this patent: a source of lubricant with the suction duct for therefrigerant vapor, said duct being formed at UNITED STATES PATENTS leastin part by two closely-spaced concentric 5 Number Name Date wallsholding between them a cylinder of gauze so 1,687,780 Neale Oct. 16,1928 that lubricant has to flow longitudinally through 1,731,774 GurleyOct. 15, 1929 said gauze cylinder, thereby filtering the lubricant1,858,817 Carrey May 17, 1932 and controlling the rate of its admissionto the 10 1,947,586 Fletcher Feb. 20, 1934 suction d 2,167,057 SaffordJul 25, 1939 ERIC GEORGE ROWLEDGE. 2,236,088 Doeg Mar. 25, 1941 JOSHUAWHJSON KITSON- 2,236,112 Philipp Mar. 25, 1941

